38 SECTIONAL ADDRESSES 



searching for a clear physical picture of the results of his investigations, 

 was capable of a philosophic breadth of view which needs surprisingly 

 little modification to-day. He makes, for example, a physical picture of 

 matter as formed in ' solid, massy, hard, impenetrable, moveable par- 

 ticles,' and assumes that they have not only a Vis Inertice, but are moved 

 by certain active principles, such as gravity. These principles are to be 

 considered ' not as occult qualities . . . but as general Laws of Nature 

 . . . their Truth appearing to us by Phaenomena. . . . To tell us that 

 every Species of Things is endowed with an occult specifick Quality by 

 which it acts and produces manifest effects, is to tell us nothing ; but to 

 derive two or three Principles of Motion from Phasnomena and afterwards 

 to tell us how the Properties and Actions of all corporeal Things follow 

 from these manifest Principles would be a very great step in Philosophy, 

 though the Causes of those Principles were not yet discovered ; and 

 therefore I scruple not to propose the Principles of Motion above 

 mentioned, they being of very general extent, and leave their Causes to 

 be found out.' Evidently Newton takes the view that we have made an 

 important step forward when we have subsumed a number of perceptual 

 facts under a general formula. 



It is to Hume, though he may owe something to Glanvil and other 

 predecessors, that we are indebted for a clearly ordered statement of the 

 experientialist doctrine of causation. The generalisation, for example, 

 that the earth attracts a stone is explained as a generalisation from thousands 

 of observations. ' Adam . . . could not have inferred from the fluidity 

 and transparency of water that it would suffocate him, or from the light 

 and warmth of fire that it would consume him. No object ever discovers 

 by the qualities which appear to the senses, either the causes which pro- 

 duced it or the effects which will arise from it ; nor can our reason, 

 unassisted by experience, ever draw any inference concerning real existence 

 and matter of fact.' 



Mill further developed the experientialist doctrine in the statement that 

 the law of causation ' is but the familiar truth that invariability of succes- 

 sion is found by observation to obtain between every fact in nature and 

 some other fact which has preceded it, independently of all considera- 

 tions respecting the ultimate mode of production of phenomena, and of 

 every other question regarding the nature of things in themselves.' To 

 the doctrine of succession in this simple form the objection has been urged 

 that day may be regarded as the cause of night and conversely. Mill 

 meets this objection by pointing out that invariable sequence does not 

 necessarily involve causation. To involve causation the sequence must 

 not only be invariable but unconditional. The day-night sequence is 

 conditional by the sun and so does not conform to this test. ' We may 

 define, therefore, the cause of a phenomenon to be the antecedent, or the 

 concurrence of antecedents, on which it is invariably and unconditionally 

 consequent.' 



It is difficult to sum up Pearson's attitude to the problem of causality 

 and to the general problem in a few sentences. Perhaps Kirchhoff's 

 dictum concerning mechanics : 'Die Mechanik ist die Wissenschaft von 



